nir: Make nir_ssa_def_rewrite_uses take an SSA value

This commit replaces the new_src parameter of nir_ssa_def_rewrite_uses()
with an SSA def, removes nir_ssa_def_rewrite_uses_ssa(), and rewrites
all the users as needed.

Reviewed-by: Rhys Perry <pendingchaos02@gmail.com>
Acked-by: Alyssa Rosenzweig <alyssa@collabora.com>
Acked-By: Mike Blumenkrantz <michael.blumenkrantz@gmail.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/9383>

src/intel/compiler/brw_fs.cpp

@@ -8953,7 +8953,7 @@ brw_nir_demote_sample_qualifiers(nir_shader *nir)
                nir_load_barycentric(&b, nir_intrinsic_load_barycentric_centroid,
                                     nir_intrinsic_interp_mode(intrin));
             nir_ssa_def_rewrite_uses(&intrin->dest.ssa,
-                                     nir_src_for_ssa(centroid));
+                                     centroid);
             nir_instr_remove(instr);
             progress = true;
          }